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- Duration: 4:06
- Updated: 21 Aug 2013
Η πρώτη "Καλημέρα" της ΔΤ
Πρεμιέρα έκανε σήμερα η πρωινή ενημερωτική εκπομπή της Δημόσιας Τηλεόρασης "Πρωινή Ενημέρωση".- published: 21 Aug 2013
- views: 11784
ΔT, Delta T, delta-T, deltaT, or DT is the time difference obtained by subtracting Universal Time (UT) from Terrestrial Time (TT): ΔT=TT−UT.
Universal Time is a time scale based on the Earth's rotation, which is somewhat irregular over short periods (days up to a century), thus any time based on it cannot have an accuracy better than 1 : 108. But the principal effect is over the long term: over many centuries tidal friction inexorably slows Earth's rate of rotation by about +2.3 ms/day/cy. However, there are other forces changing the rotation rate of the Earth. The most important one is believed to be a result of the melting of continental ice sheets at the end of the last glacial period. This removed their tremendous weight, allowing the land under them to begin to rebound upward in the polar regions, which has been continuing and will continue until isostatic equilibrium is reached. This "glacial rebound" brings mass closer to the rotation axis of the Earth, which makes the Earth spin faster (law of conservation of angular momentum): the rate derived from models is about −0.6 ms/day/cy. So the net acceleration (actually a deceleration) of the rotation of the Earth, or the change in the length of the mean solar day (LOD), is +1.7 ms/day/cy. This is indeed the average rate as observed over the past 27 centuries.
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Shakira
T
Te regalo mi cintura,
Y mis labios para cuando quieras besar,
Te regalo mi locura
Y las pocas neuronas que quedan ya.
Mis zapatos desteidos,
El diario en el que escribo,
Te doy hasta mis suspiros,
Pero no te vayas ms,
Porque eres t mi sol,
La fe con que vivo,
La potencia de mi voz,
Los pies con que camino,
Eres t, amor,
Mis ganas de rerme,
El adis que no sabr decir
Porque nunca podr vivir sin ti.
Si algn da decidieras,
Alejarte nuevamente de aqu,
Cerrara cada puerta,
Para que nunca pudieras salir.
Te regalo mis silencios,
Te regalo mi nariz,
Yo te doy hasta mis huesos,
Pero qudate aqu,
Porque eres t mi sol,
La fe con que vivo,
La potencia de mi voz,
Los pies con que camino,
Eres t, amor,
Mis ganas de rerme,
El adis que no sabr decir
Porque nunca podr vivir sin ti.